Included in C. laucha by Hershkovitz (1962) but morphological and karyotypic evidence supports its specific status (Corti et al., 1987; Massoia et al., 1968). Sister species to C. lepidus according to phylogenetic interpretation of cytochrome b sequences (Salazar-Bravo et al., 2001). Morphometric variation among select phytogeographic samples examined by Provensal and Polop (1993); allozymic variability among samples in EC Argentina investigated by Gardenal et al. (2002) and contrasted with sympatric C. laucha. Synonymy follows Massoia et al. (1968) and Contreras and Rosi (1980), who considered murillus a subspecies of C. musculinus; others have treated the former as a species (Olds, 1988; Reig, 1986). In the molecular study of Salazar-Bravo et al. (2001), it is noteworthy that their sample of C. musculinus from Buenos Aires Province, presumably referable to murillus proper (type locality La Plata, Buenos Aires Prov.), was genetically like population samples drawn from NW Argentina, presumably referable to musculinus proper. Until the issue can be substantively resolved, we continue to view murillus as a subjective synonym.